SVS CS-Ultra / Amp Question

Discussion in 'Archived Threads 2001-2004' started by Gary Thomas, Dec 26, 2001.

  1. Gary Thomas

    Gary Thomas Second Unit

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    I've recently hooked up an Ultra driven by a Fidek 4002 amp. I'm using 1 channel of the stereo amp - 400w. The Sub is corner placed in a large family room that opens to a kitchen, hallway, etc.

    I'm very happy with the sub...a definite improvement over my prior HSU-VTF 2.

    The problem I'm having is that I can't get the sub to reference level when calibrating. I have the amp volume turned to max & the sub level on my Denon 3802 set to a max of +12. While my speakers are calibrated to 75db, I can only get the sub up to 70db. (I'm still getting huge output...but would prefer to set the sub level on the receiver at 0 or below)

    Should I try the amp bridged at 800w...or is that too much for the sub?
     
  2. SVS-Ron

    SVS-Ron Screenwriter

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    Gary,

    This is almost certainly NOT a power level issue (unless you hare setting up the sub in the opposite end of a an aircraft hangar? ;^). So you should not need to bridge the Fidek, it's not recommended anyway since it's not rated to drive 4 Ohm loads in bridged config.

    Making sure everything is off, swap out your LFE/Sub cable, and make darn sure you are using a good, NEW RCA to 1/4" MONO input adaptor. It MUST be a mono connector or your input will be flawed at best.

    Then check to see if there are ANY limiters of any kind on your Denon. Check all the obvious and not so obvious settings and connections. Something is not set right. You should be able to EASILY exceed 70dB on setup. If you haven't already, try the other channel on the amp too. It could be that one channel is bad. A longshot but worth trying.

    If you haven't already, make sure you get Avia or Video Essentials going as your test tones. Receiver test tones are not always the most reliable way to driver subwoofer calibration.

    Let us know what you discover. Something's amiss.

    Ron
     
  3. Gary Thomas

    Gary Thomas Second Unit

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    Ron:

    A little more info:

    The Denon has a single sub-output. I have that split, with one line going to an old receiver to power some bass shakers and the other line going into an ART 351 eq. I have Radio Shack Gold mono-adapters in & out of the eq, then in to the Fidek. I'm using 12ga. Monster speaker cable out to the amp.

    I guess I could try running the sub-output directly to the eq to see if that is where I'm losing the signal. I wonder if there is another work around to power the shakers??? I don't want to use the Fidek because I would like to control the shaker effect independently.
     
  4. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Sounds like the problem is that you don't have enough signal gain. You could try moving the EQ levels up if you're not already maxing it at some frequency. If you move all the levels up equally then you should get the gain you need without hurting the frequency response.

    Alternatively you could change the speaker levels in your receiver for all your other speakers. If you bring them all down 5dB then you sub should be level with them and your new reference level would be +5 rather than 0.
     
  5. SVS-Ron

    SVS-Ron Screenwriter

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    Gary,

    Since the ART has its own independent level control, is it possible that is set too low?

    It should be at least half up, or higher.

    Ron
     
  6. Gary Thomas

    Gary Thomas Second Unit

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    The ART level was on 7. Should I max it to 10?
     
  7. SVS-Ron

    SVS-Ron Screenwriter

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    Shouldn't need to. If you have checked out everything else I mentioned (might even mean diving into the Denon manual ;^( then certainly turning up the eq level control might help some.

    Feel free to e-mail us on this, we tend to catch notes quicker than forum posts FWIW. Did you get the Fidek from us? IF you ran thru everything, then either the Denon is putting out a lower than typical LFE/subwoofer voltage for some reason, or the Fidek has an "issue".

    Ron
     
  8. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    Yes, max the art out as needed.

    You can also increase the output level from the art by using the individual sliders too.

    Bridging the fidek might help...but 400w into the CS_U should be plenty really.

    Let me know if increasing the art gain helps either here or via private email,

    TV
     
  9. Gary Thomas

    Gary Thomas Second Unit

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    Here's the latest:

    I increased the gain on the ART to max, checked all of the interconnects, switched to the other Fidek amp, eq'd to an excellent 1/3 octive curve(still have 1 big dip at 72hz that the ART can't reach), and checked the level using both the Denon test tones and VE test tones (almost exactly the same).

    With all of my speaker levels set right on 70hz, the sub only registers in the low 60's...even though the ART gain is max, the Denon sub level is max and the Fidek volume is at max.

    But... with program material I get a huge bass response. On a demo dvd w/ the Titan AE track I actually bottom out the sub at -10db volume setting. (0db is reference) I do have the EQ high pass set at 15hz.

    So, for now I've reduced the Denon sub level to 0, based on listening to the Titan AE demo track. I'm going to live with this for a week or so, then decide if I need to check anything else.

    It seem as though the level setting response just doesn't match the response with program material.
     
  10. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    Sounds like you're using the receivers internal test tones for calibration. Have you tried Avia or VE or possibly even THX Optimode?
     
  11. SVS-Ron

    SVS-Ron Screenwriter

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    Good question Ryan (I asked the same thing yesterday).

    Using a disk is critical to validating an issue like this. How about it Gary?

    Ron
     
  12. Bruce N

    Bruce N Second Unit

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    You could try bypassing everything by running one interconnect from the receiver directly to the Fidek. No ART, no Y connector. This would eliminate the ART or your Y connection as the culprit.

    It does sound like the internal test tones are the problem. Another vote for using a calibration disc.

    Hope this helps!

    Bruce
     
  13. Gary Thomas

    Gary Thomas Second Unit

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    Yep. I did calibrate using the Video Essentials dvd. The relationship between the subwoofer level and other speaker levels were almost exactly the same as the Denon 3802 internal test tones.
     
  14. SVS-Ron

    SVS-Ron Screenwriter

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    Interesting Gary.

    It seems the Denon is doing something odd here, the fact you can bottom (a damn hard to bottom sub like the CS-Ultra) sub is proof enough that you are getting high levels of bass. Maybe in the end you will want a second Ultra if you are looking for that feel, and avoiding bottoming.

    Either way I think the Fidek and sub are working, but those measurements are confusing, no doubt about it.

    Ron
     
  15. John Cain

    John Cain Second Unit

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    Hi Gary, I'm in a very similar situation.

    Not a lot of bass, but the sub bottoms out.

    I'm not going to panic yet, because the sub is not in my actual HT which is under construction.

    I'll worry if I move it down there and have the same situation.

    -- John
     
  16. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    There could be an input impedence mismatch between the voltage output of the denon's subwoofer preout jack and the amp's input stage.
    But this wouldn't explain the extra-loud levels during source material. It seems likely there's some mistake being made in the calibration process. As mentioned, take the EQ out of the loop for now...eliminate that variable(good idea btw [​IMG] ).
    Do you still have the *LFE* level at it's default setting in the speaker setup menu?
    Try the calibration tones again....but instead of sitting at the same seat...try moving around.(try standing about 1m from the subwoofer too).
    Does the needle move up much?(your key seat might be in a null...throwing off the calibration a little).
    We'd be glad to exchange the subwoofer for a brand new unit of course...but I just don't think that's the problem.
    Have you tried running the subwoofer out of phase?
    TV
     
  17. Gary Thomas

    Gary Thomas Second Unit

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    Tom / Ron...thanks for the feedback.

    I've figured it out!!! The reason I was getting a poor response on my sound level meter & a huge response w/ program material was that I had the meter inadvertently set to A weighting rather than C weighting! The A weighting only covers higher octives.

    Just goes to show that we should all trust our ears. I have now re-calibrated the sub at 76-78db's with all the other speakers at 75db and have the following settings:

    Amp: Full level

    EQ: 75% level

    Denon Receiver Sub Setting: -5db

    The bass is full, tight & smooth. It blends perfectly with my other speakers.
     
  18. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    Gary, that's GREAT to hear.
    Ron and I have had several chats about your situation and we couldn't figure out what was going on. We'll add this to the general *list* of things to double check on. It definitely explains why the bass seemed so loud to you to start with [​IMG]
    TV
     

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